MCQs on Design of Helical Springs
1 - Question
If a spring has plain ends then number of inactive coils is?
a) 1
b) 2
c) 3
d) 0
View Answer
Answer: d
Explanation: There are no inactive coils in plain ends.
2 - Question
Spring having square ends has 1 inactive coil.
a) True
b) False
View Answer
Answer: b
Explanation: There are 2 inactive coils.
3 - Question
Martin’s factor compensates for curvature effect in springs.
a) True
b) False
View Answer
Answer: b
Explanation: Wahl’s factor accommodates curvature effect while designing spring.
4 - Question
The angle of twist for the equivalent bar to a spring is given by? (Symbols have their usual meaning)
a) 8PD²N/Gd⁴
b) 16PD²N/Gd⁴
c) 16PDN/Gdᵌ
d) 8PDN/Gdᵌ
View Answer
Answer: b
Explanation: θ=Ml/GJ where M=PD/2, l=πDN and J=πd⁴/32.
5 - Question
The axial deflection of spring for the small angle of θ is given by?
a) 328PDᵌN/Gd⁴
b) 8PDᵌN/Gd⁴
c) 16PDᵌN/Gd⁴
d) 8PD²N/Gdᵌ
View Answer
Answer: b
Explanation: Deflection=θxD/2.
6 - Question
A spring of stiffness constant k is cut in two equal parts. The stiffness constant of new spring will be k/2.
a) True
b) False
View Answer
Answer: b
Explanation: k=Gd⁴/8DᵌN, hence k is inversely proportional to number of coils. Thus result will be 2k.
7 - Question
For two spring connected in series, the force acting on each spring is same and equal to half of the external force.
a) True
b) False
View Answer
Answer: b
Explanation: Te force on each spring is equal to the external force.
8 - Question
For two springs connected in series, the net deflection is equal to the sum of deflection in two springs.
a) True
b) False
View Answer
Answer: a
Explanation: The net deflection is sum of the deflection of sprigs connected in series.
9 - Question
For two springs connected in parallel, net force is equal to the sum of force in each spring.
a) True
b) False
View Answer
10 - Question
Patenting is defined as the cooling below the freezing point of water.
a) True
b) False
View Answer
Answer: b
Explanation: Patenting is heating steel above critical range followed by rapid cooling.
11 - Question
Find the Wahl’s factor if spring index is 6.
a) 1.2020
b) 1.2424
c) 1.2525
d) 1.5252
View Answer
Answer: c
Explanation: K=[4C-1/4C-4]+0.615/C.
12 - Question
Find the shear stress in the spring wire used to design a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
a) 452.2N/mm²
b) 468.6N/mm²
c) 512.2N/mm²
d) None of the listed
View Answer
Answer: b
Explanation: τ=K x 8PC/πd² where K=[4C-1/4C-4]+0.615/C.
13 - Question
Find the mean coil diameter of a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
a) 7/6mm
b) 42mm
c) 1200×6/7 mm
d) None of the listed
View Answer
Answer: b
Explanation: D=Cd.
14 - Question
Find total number coils in a spring having square and ground ends. Deflection in the spring is 6mm when load of 1100N is applied. Modulus of rigidity is 81370N/mm². Wire diameter and pitch circle diameter are 10mm and 50mm respectively.
a) 7 b) 6 c) 5 d) 4
View Answer
Answer: a
Explanation: Deflection=8PDᵌN/Gd⁴ or N=4.4 or 5. Total coils=5+2(square grounded ends).
15 - Question
A railway wagon moving with a speed of 1.5m/s is brought to rest by bumper consisting of two springs. Mass of wagon is 100kg. The springs are compressed by 125mm. Calculate the maximum force acting on each spring.
a) 1200N
b) 1500N
c) 1800N
d) 2000N
View Answer
Answer: c
Explanation: mv²/2=Pxdeflection/2.